Knog Cobber Big Rear Light

The Knog Big Cobber Rear light uses its swooping wraparound design and 270-lumen output to fire almost blindingly obvious signs of life into overtaking traffic (assuming there's any intelligent life there to receive them). You can check it's on without performing contortions, eight useful modes give between two and 100 hours of burn-time, and it's simple to use. The low battery warning is inadequate, however, and it takes ages to charge.

• Pros: Bright, lightweight, 330-degree coverage, USB rechargeable
• Cons: Low battery warning doesn't come soon enough, long charging time, expensive

The Big Cobber is a simple design that works really well in almost every way. A long press of the single button switches it on or off, short presses cycle the modes, and a red ring indicates low power/still charging. Once it's 100 per cent charged, the ring goes green.

On the road, however, that ring only lights red with less than 15 minutes to go – I can't narrow it down further as it tended to silently die between checks without me ever even seeing it. There's no other way of checking battery status, and the 5.5hr charging time (on a mains adaptor – a computer is slower still) means there's no quick fix.

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This means it's not good for long or multiple rides unless you're careful with your mode selection; the five main flashing options can be mistaken for each other, and their run-times vary between 6.5hrs (Flash) and just 2hrs (Side Flash). Yes, there's a 100hr Eco Flash, but it's more off than on and only gives 15 lumens.

That said, Knog lists run-times for each mode and they're very accurate, so as long as you're careful it's an excellent light. Knog also calls it a commuter light, so perhaps it's not fair to judge it for longer rides, but a) it's potentially excellent for them and b) the mystery battery status and nearly workday-long charging time pose the same problems for commutes.

The whole thing is re-programmable via Knog's Modemaker app, if you really want to fine-tune the flickering, but quite how many rear-light enthusiasts are looking to go that far is up for debate.

The simple 6g o-ring bracket is stickily soft-backed and more than enough to support the 56g unit, and slides securely into grooves to stick with both friction and a magnet. You even get a second bracket in the box shaped to fit aero posts.

Removing the bracket reveals the male USB connector, and though it's well covered it's apparently designed to cope with water anyway, which is sensible. I had no issues with it degrading or even getting particularly dirty during the test.

The light unit is neatly made, well sealed and solid enough, though it stops short of feeling particularly tough – the plastic is stiff and inflexible, and you probably wouldn't want to drop it on concrete too regularly. The bracket is a more bendy material and feels more resilient.

The 330-degree beam spread is excellent, especially for city riding or around junctions, and I particularly like that the forward-facing edges light up. It means you can check it's on with just a quick glance towards your feet – it's bright enough to show in your peripheral vision even in the day – rather than throwing crazy shapes across the road trying to peer under your own bum.

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There are similarly bright lights available for less, such as the £45 NiteRider Omega 300, but dodgy waterproofing restricts that to dry rides only. Blackburn's DayBlazer 125 is less powerful but still bright enough for day or night, and also £45, while Lezyne's excellent if slightly clunky Strip Drive Pro 300 is £50 and shoves out 300 lumens for five hours.

None have quite the wraparound loveliness of the Big Cobber Rear, but it's hard to argue with lower prices, faster charging and – certainly in the Lezyne's case – a more reassuringly sturdy build.

Note that Knog's own medium-sized Cobber is £60 and fundamentally the same, just smaller and, at 170 lumens, less powerful.

Overall, the Knog Big Cobber is a very bright, very eye-catching rear light that's easy and pleasurable to use, but slightly let down by the lack of a meaningful status indicator, long charging times and a high price. Under careful and considered use it is, however, excellent.

Verdict

Really bright and safe rear light, but expensive and some battery niggles